A variety of apparatus for wet processing photo. sensitive material are known, for example, silver salt photographic copying machines and automatic developing machines.
The silver salt photographic copying machine is designed to reproduce a copy from an original image by supplying a photosensitive material typically in the form of a color paper web from a paper source to an exposure zone where the web is exposed, transferring the exposed web to a processing zone where it is successively subjected to development, bleach-fixation and rinsing, and finally drying the web in a drying zone. The automatic developing machine is designed to produce a negative or positive image by successively subjecting an exposed photosensitive material typically in the form of a color negative film to development, bleaching, fixation, rinsing, and stabilization in a processing zone and finally drying the film in a drying zone. The drying apparatus used in each drying zone of these photosensitive material processing apparatus includes a duct surrounding a path for carrying the photosensitive material and a heater and fan for blowing warm air into the duct whereby while the photosensitive material is being conveyed through the duct in a wet state, warm air is blown onto the photosensitive material for drying.
These prior art drying apparatus have a drawback that although a large volume of warm air is supplied because of the large volume of the duct interior space, only a small proportion of warm air actually contacts the surface of the photosensitive material and thus contributes to water removal. Because of such inefficient utilization of warm air, it takes a long time to fully dry the photosensitive material. A long drying time is one of bars against the demand for shortening the total processing time particularly in wet type copying machines and automatic developing machines.
Besides, heating a large volume of air requires a large quantity of energy consumption. In addition, a correspondingly large quantity of waste heat is exhausted to the exterior, imposing undesirable effects like temperature and humidity increases to the environment where the machine is installed. Also undesirably, it takes some time to heat up at the start of operation.
The increased heat-up time makes it unfeasible to turn on and off the drying apparatus every time when it is desired to process photosensitive material. The drying apparatus should be continuously turned on irrespective of whether or not the photosensitive material is processed, also inviting an increase of energy consumption.
The prior art drying apparatus has a serious influence on the emulsion layer of photosensitive material. The prior art drying apparatus is designed such that once warm air is supplied into the duct and utilized for drying, about 70 to 95% of the warm air is recovered for recycle to the duct. When a large quantity of photosensitive material is continuously processed, the material is dried with incrementally humid warm air from some time on, causing defects such as reticulation and crazing on the emulsion surface of photosensitive material.
Japanese Utility Model Application Kokai No. 44331/1973 discloses a drying apparatus for photographic processing, which belongs to the same technical field as the present invention. This reference shows an apparatus for drying photosensitive material with hot air between feed rollers and take-out rollers. Drying air is heated hot and passed over the surface of photosensitive material in the interior of the apparatus for drying the material. The drying apparatus includes discharge means for discharging the drying air which has completed drying and thus picked up some moisture through a portion of the drying apparatus.
The objects of the known drying apparatus for photographic processing are to accomplish drying in a short time and to pneumatically convey the photosensitive material with the air flow through the transfer path (which corresponds to the slit-shaped interior space of the present invention as will be disclosed later), but pays no attention to the control of the humidity difference between the beginning and the end of drying. For this reason, the entire longitudinal distance of the transfer path of the drying apparatus is short, that is, only about 2 to 3 times the total length of the blowing openings of the nozzle. The Kokai reference does not indicate a need for dehumidifying means because the used drying air is discharged out of the apparatus. The known drying apparatus for photographic processing cannot achieve a difference of at least 30% RH in relative humidity between areas in the transfer path near the beginning and the end of drying, thus failing to avoid defects like reticulation on the photosensitive material emulsion surface.